RAHWAY — A long-time county freeholder and powerful Democrat was appointed Wednesday night to an interim role as the head of the Union County Utilities Authority, officials said.

Daniel Sullivan, a past assistant chief administrator at the state Motor Vehicle Commission, takes over following the resignation of the agency's last executive director, Sunnil Garg.

Garg stepped down about a week ago, according to Sebastian D'Elia, a county spokesman who did not immediately offer an explanation for the departure.

Sullivan, also the current chairman of the North Jersey Transportation Planning Authority, will forgo his freeholder salary and benefits package while heading up the utility authority, the county said in a statement announcing his appointment. As Interim Director, Sullivan will be paid an annual salary of $130,000, and serve the UCUA Board through April 19th of next year. Garg was paid $153,000 in 2010, according to public records.

Sullivan, an Elizabeth resident, has been a freeholder liaison to the authority and is credited with helping save it from insolvency in 1998. In that year, the authority signed a lease agreement with a company named Covanta, which currently operates the county's solid waste incinerator. The facility uses heat generated from burning garbage to create electricity.

Sullivan said his top priority is to finalize a long-term lease renewal with Covanta, a deal that's been in the works since last year. The lease extension, plus a 5-year renewal option, would last until 2031 and result in an additional $70 million in revenue, officials said.

"With local governments suffering from revenue reductions, it is more important than ever that we seek to maximize an asset can help deliver tax relief to our taxpayers," Sullivan said in a statement. "We achieve this while guaranteeing that our municipalities maintain low disposal rates."